1) Field of the Invention
The present invention relates to a process for preparing a bulky synthetic pulp sheet which does not lose shape even after having absorbed liquid and to a process for preparing the same. More specifically, the invention relates to a bulky synthetic pulp sheet having excellent resistance against chemicals such as acids, alkalis, etc. in addition to the above-mentioned property and to a process for preparing the same. The invention further relates to a sealed-type lead battery and a separator for cells.
2) Description of the Related Art
Methods have heretofore been proposed for preparing bulky sheets that are used for absorbing liquids or are used as buffer members for imparting elasticity. These methods use a cellulose pulp as a chief material and further add, for example, folded synthetic fibers (Japanese Laid-Open Patent Publication No. 132900/1989) or three-dimensionally crimped synthetic resin fibers (Japanese Laid-Open Patent Publication No. 269199/1991) in order to impart bulkiness.
However, these bulky sheets which are chiefly composed of a cellulose pulp are inferior in resistance against chemicals, and are not suited for such applications as absorbing and holding strongly acidic liquids such as sulfuric acid and the like acid.
Therefore, it has been strongly demanded to provide articles capable of absorbing chemicals that are leaked or spilled and capable of holding an electrolyte therein, like a separator used in a sealed-lead battery, that can be cheaply produced and used safely.